Relationship between pyrimidine dimers, 6-4 photoproducts, repair synthesis and cell survival: studies using cells from patients with trichothiodystrophy.
Trichothiodystrophy is a genetic disease which in the majority of cases studied is associated with a deficiency in the ability to repair UV damage in cellular DNA. Three categories of UV response have been identified. In type 1 the response is completely normal, whereas type 2 cells are deficient in excision-repair, with properties indistinguishable from those of XP complementation group D. Type 3 cells have normal survival following UV-irradiation and normal rates of removal of cyclobutane pyrimidine dimer sites. Nevertheless repair synthesis is reduced by 50% in these cell strains and this is associated with a marked reduction in the repair of 6-4 photoproducts from cellular DNA. The present results show that 50% or more of repair synthesis at early times after irradiation of normal primary human fibroblasts is attributable to repair of 6-4 products. They also suggest that repair of cyclobutane dimers is crucial for cell survival.
Broughton
B C
BC
MRC Cell Mutation Unit, University of Sussex, Falmer, Brighton, Great Britain.
Lehmann
A R
AR
Harcourt
S A
SA
Arlett
C F
CF
Sarasin
A
A
Kleijer
W J
WJ
Beemer
F A
FA
Nairn
R
R
Mitchell
D L
DL
D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured; D002675:Child, Preschool; D004247:DNA / Q000528:radiation effects*; D004260:DNA Repair; D005260:Female; D005347:Fibroblasts / Q000528:radiation effects; D006201:Hair Diseases / Q000235:genetics*; D006801:Humans; D011740:Pyrimidine Dimers / Q000378:metabolism*; D014466:Ultraviolet Rays
D011740:Pyrimidine Dimers; D004247:DNA